This Tokay gecko (scientific name Tokay tokay) is opening its mouth in defence as it feels threatened. Tokay geckos are one of the more aggressive geckos, often known as the bulldog of geckos . Its rare that you can approach them without the gaping like this , both as a defence and to scare of predators. The frequently bite, so dont make for the best pet if you want to handle your lizard. They are skittish and move extremely fast, so are more suited as a pet that you observe rather than handle.
Your right Tokays arent good for new lizard owners, Bearded dragons, Leopard geckos and Crested Gecko are the best lizard pet for any new lizard owner.
I do too. I think it's one of the things that I love about any herptile. No matter how "tame" they may seem they all have a "tokay gecko" attitude that they can switch on at any moment. It's that, that any herp keeper has to always keep in the back of their heads.